HFU HF Underground
Loggings => North American Shortwave Pirate => Broadcast Announcements => Topic started by: jackson_r on November 27, 2015, 0346 UTC
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I'm going to be trying on 6920 AM about 10 minutes from this posting, and will continue for about 20-25 minutes.
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I checked the SDR recording, no sign of a carrier.
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I show no activity on 6920 kHz from 0352 to 0435 UTC on the overnight SDR recording.
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Thanks for the report, rather lack thereof. :D I'm only running at 50 watts in to a 6' whip that's mounted just 5 feet above the ground. Unfortunately with my HOA rules, I don't have many options as I have to keep it out of sight. I'm going to look at doing some different positioning this weekend, might try on USB as well after I do that.
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6' whip at 5 feet may get you 2 blocks with a CB radio but on 40m your going to need something a bit longer!
For NVIS a dipole made from thin (invisible) wire can be 7' from the ground and can run along a fence top but will need to be 70' long.
I've done some experiments recently and can put a decent signal into Holland from the U.K. about 400 miles with 10W.
This will only work during daylight hours, so your going to need a 35' vertical at night and you'd probably work from coast to coast, 2000 miles or so.
Use what you can but don't expect you're going to get anywhere with a 6' antenna at these frequencies.
OK!
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6' whip at 5 feet may get you 2 blocks with a CB radio but on 40m your going to need something a bit longer!
For NVIS a dipole made from thin (invisible) wire can be 7' from the ground and can run along a fence top but will need to be 70' long.
I've done some experiments recently and can put a decent signal into Holland from the U.K. about 400 miles with 10W.
This will only work during daylight hours, so your going to need a 35' vertical at night and you'd probably work from coast to coast, 2000 miles or so.
Use what you can but don't expect you're going to get anywhere with a 6' antenna at these frequencies.
OK!
I appreciate the cold hard truth, Stretchy. I actually do have a 40 m dipole sitting in a box that I've been thinking about stringing across the top of my 6.5' privacy fence in the back yard. Plenty of room, but the only thing that's kept me from trying it is first, that I'd have to run about 100' of coax to get out there from the shack, and also the fact that I've read somewhere that a fence top mounted dipole like that is going to be very focused and directional, and I didn't know if that was going to cause me problems. But I'm willing to try anything once. :)
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You could also try a magnetic loop. Those things are high performance for their size. Make a 9' diameter bad boy out of plumbing copper pipe!
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and I forgot to mention the 1 KW amplifier I have arriving in the first week of December. That should help me play with the big boys. Or maybe something will explode. Either way, it is exciting. ;D
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OK with the amp but you'll do fine with 10W and an antenna that works.
1KW will probably just wipe out all the local phone/tv/radio etc and get you into a heap of trouble.
The loop BTW is a good antenna but your situation (as I understand it) needs something more covert.
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OK with the amp but you'll do fine with 10W and an antenna that works.
1KW will probably just wipe out all the local phone/tv/radio etc and get you into a heap of trouble.
The loop BTW is a good antenna but your situation (as I understand it) needs something more covert.
Well, I was being a bit facetious. While it's indeed a 1 KW amp, I have no intention of using it as such. Once I get a good antenna up and running, I might use it to drive 200-300 watts occasionally. Today I'm going to tack down my 40 meter dipole on the backyard fence and see what that does.
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Cool, no worries. Try a folded dipole low to the ground, the Z will drop and you'll get a decent swr. As long as you have a good take off you'll get fair NVIS. Let us know how u get on.Plenty of online SDRs now to test your metal!
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trust me.
the urge to push more than 200-300 watts will eventually overcome your resistance to do it ;D
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trust me.
the urge to push more than 200-300 watts will eventually overcome your resistance to do it ;D
Oh, I don't doubt. But as I mentioned in another thread here, that last thing I want to do is start blasting across the neighbor's baby monitor. ;D
I continue to be intrigued by the magnetic loop antenna option. I spent the better part of the weekend reading up on them and it's definitely something within my skill set to make. The way our backyards are clustered together, I doubt I could get away with mounting a 9' loop vertically. Even in the dark, it would look like some sort of UFO had landed in my backyard. But I've been reading that horizontal mountings can work as well, and that would be a lot less noticeable to the nosy nellies who live next door. I'm going to try the fence mounted dipole first. If that doesn't work, I'll consider the mag loop.
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Make sure wire is 'insulated' from fence, wood gets wet and antenna would perform poorly.
Optimum NVIS height is only 8'.
Yes I've been looking into loops as most folk TX on a fixed Freq, make the ideal antenna using a vacuum (fixed) 100pF cap and 22' loop, should give me close to 6.4MHz resonance.
Mounting horiz, you really want to get some height but as you really after NVIS? I guess mounting low may be fine?
Have fun experimenting!
With the wealth of online SDR's it's easy to see if it's working!
Stretchy.
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with my testing and experience through the many years, if youre going to mount a horizontal dipole, i find that 30 feet above ground with at least 10 feet from absorption obstacles seems to be at the minimum threshold for optimum performance but not everyone can afford this luxury.
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Stretchy - I've read some sources that say a properly resonant mag loop antenna will work just fine, even mounted vertically on the ground. :o If that's true, I may be able to use one with a vertical orientation and still keep it fairly out of sight. I guess we'll find out if I end up going down that path. Right now I have to wait a few days before I can even try my fence dipole. I had to order in 150' of coax to even make the connection from my rig. :D
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OH, I though he wanted NVIS?
Your 'Distances' are so much 'Larger' over there!
:D
Str.
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Yes the loop will be very good and will radiate low and high angle radiation so give you good coverage (local, aka NVIS & DX) when mounted close to the ground.
Remember the rather high voltages which will be around even with 100W = 5KV! so keep it at 10' or so.
You on the E or W coast?
Or somewhere in between?
Str.
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West Coast of the U.S.
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The west is the best they say!
OK, where's your 'Target' audience?
Fellow West coasters, East Coast, Europe or anywhere else?
Str.
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I would say all points "east." I'd prefer to attenuate to the west as the feds have an outpost there. ;) It's an interesting question that I was going to ask as part of this tangent we've taken on mag loops. From what I understand, mag loop antennas have a specific area of attenuation out of the axis. So if I mounted a mag loop horizontally, RF is going to go out in an omnidirectional pattern with attenuation directly beneath and above the axis. Mounted vertically (and lets say in an east/west orientation), the pattern would be straight up and north/south with attenuation to the west and east. Orient it north/south and the pattern would be straight up and west/east, with attenuation to the north and south. Sorry, that all looks like rambling upon reading it again, but I'm just struggling to wrap my pea brain around the directional characteristics of a mag loop antenna.
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Yes the pattern seems the opposite of what You think!
Would be a good antenna for sure, quite a bit of effort.
As your already west I can't work out where the Feds are, on a boat or in Hawaii!
(http://:D)
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The little buggers are everywhere, aren't they? I'm actually about 50 miles inland from the coast and I've got a big metro city due west of me where they have an office. Not to mention that I've got a couple of Ham towers due west of me in the neighborhood (different HOA, hence the reason they can have a visible antenna and I can't). I'd rather stay out of their line of "sight" if possible. I was thinking of orienting a mag loop north/south, with a big piece of plywood wrapped on one side with aluminum foil just a couple of feet to the west of the it. From what I've read, this should attenuate the signal quite a bit to the west, or at the very least throw people from the west "off" about where the signal is coming from. I may never build one, but I like antenna theory. :D
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You could camouflage the loop by painting it white and putting fake vines and flowers on it like its a garden arch. And put a pretty box over the capacitor and paint some silly flower design on it.
Or you could also get some plastic lattice and fill in the loop with it. And put vines and large fake butterflies on it.
Here's some info from the web that I found after a month of obsessing over the mag loop things (its in my post down the page):
http://www.hfunderground.com/board/index.php/topic,23877.0.html
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Jackson,
Trying to attenuate your signal toward an FCC field office probably isn't going to help you. In fact, they don't actually do their radio monitoring from there.
Read this:
http://freeradiocafe.com/forum/viewtopic.php?f=14&t=3388
Since they monitor from multiple points around the country, it doesn't matter that much which way HF transmissions are "pointed"-- some of them will be able to pick it up.
The biggest issue is to try to avoid being reported by anyone to the FCC-- it's fielding complaints where they spend most of their enforcement energies. They don't have the resources to do much else.
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Wise words!
How true, one can not expect to completely attenuate a signal from an antenna even with a wall of lead!
The signal will bounce off all sorts of things, sure it will be less than the 'forward' direction but still radiate.
I think the 'Flower Pot' etc suggestion is superb and as the man says you're only going to get sussed if you cause interference.
Put the antenna up without even broadcasting!
Str.
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You could camouflage the loop by painting it white and putting fake vines and flowers on it like its a garden arch. And put a pretty box over the capacitor and paint some silly flower design on it.
Or you could also get some plastic lattice and fill in the loop with it. And put vines and large fake butterflies on it.
Here's some info from the web that I found after a month of obsessing over the mag loop things (its in my post down the page):
http://www.hfunderground.com/board/index.php/topic,23877.0.html
Great idea! In my HOA, my backyard can be seen from the second floor of no less than 6 different neighbors. I think what would make the most sense is to paint something like that a shade of green that closely approximates the green color of my grass. Or I guess since I'd usually be using it after dark, just to paint it black.
Good advice as well from John and Stretchy. 150' of coax for the dipole arrives today. I'll post a "heads up" here once I get ready to try it out and we'll see if I'm transmitting any better. If that doesn't do much for me, we'll start looking at decorated backyard flower arches. ;D